Plasma processing can benefit from precise control over ion energy and further from an ability to control an ion energy distribution function (IEDF) of ions incident on a substrate during processing. However, precise control is hampered by a lack of non-invasive and real-time means for monitoring ion energy and IEDF.
Additionally there are various metrics that can be monitored via a knowledge of ion current, II, and sheath capacitance, C2 (or Csheath). However, there is also a lack of systems and methods that can non-invasively and in real-time monitor these values.